The invention relates to a compounder according to the preamble of claim 1.
Compounders for mixing, for example plastics with additives such as fiber materials and other additives and colorants, to produce a generally granulated compounded material to be used for further processing normally include a screw extruder as central part for mixing various materials to be processed. The mixing units typically involved here are twin screw extruders rotating in same direction or opposite direction and operated by a drive module which normally includes an electric motor and an attached gearbox. Of course, it is also possible to provide a different drive, for example a hydraulic motor. Heretofore, such a mixing unit is typically equipped with a separate machine frame for support of the drive module and the processing unit (extruder barrel with the extrusion space). Up to now, it has been common practice to separately transport the mixing unit and the supply and discharge lines, required for operation of the mixing unit, for material being processed and auxiliary and process materials and energy as well as for measurement, control and regulation technologies as well as the required switch cabinets and auxiliary devices (e.g. weigh feeders, suction units), and to position and operatively connect them at the job site. This significantly complicates the assembly and the break-in of the compounder by the personnel of the plant manufacturer at the job site.
In order to reduce the assembly works and facilitate the break-in operation, it has been known to complete installation of at least the essential parts of the compounder, i.e. in particular the actual mixing unit with the periphery required for operation, in a three-dimensional framework already at the manufacturing factory and to transport this practically operational construction together with the three-dimensional framework to the job site, where it is only necessary to place the three-dimensional framework upon the prepared substructure and to anchor it. There is no need to lay and mount the supply and discharge lines for operation of the compounder at the job site, so that the time to commence operation is reduced to a small fraction of the otherwise typical time. Thus, the three-dimensional framework assumes hereby not only an essential function for the transport of the compounder but remains at the job site also a part of the overall plant so as to assume also the function of a mounting frame that is only required to be placed upon a substructure.
The mounting of the lines and individual units at the factory end in or on the three-dimensional framework is accompanied, however, also by a significant drawback because vibrations, caused in particular by the drive module of the mixing unit, are transmitted via the supporting frame also onto other units which are sensitive to vibrations. An example includes the weigh feeders whose precision is adversely affected by mechanical vibrations. Such vibrations may also damage electronic devices and lead, for example, to malfunction of plugged boards as a result of a loosening.
Remedies, involving an indirect connection of the mixing unit with its drive module to the three-dimensional framework through intervention of dampening elements (e.g. rubber pads), resulted in a significant but still in many cases insufficient improvement.
It is an object of the present invention to provide an improved compounder in such a way that mechanical vibrations caused by the drive module of the mixing unit are prevented from adversely affecting the operation of the compounder in a simplest possible manner.
This object is attained in accordance with the present invention by an apparatus having a mixing unit which can be mechanically driven by a drive module and is provided with one or more feed devices for the material to be processed and one or more additives to be mixed with this material, wherein the mixing unit is disposed in a supporting frame configured as a three-dimensional framework, and wherein the supply and discharge lines required for operating the mixing unit, for material to be used and auxiliary or process materials and energy as well as for measurement, control and regulation technologies are substantially completely installed in or on the supporting frame and are connected to the mixing unit, wherein the supporting frame is configured as a transport frame for the transport of the compounder to the job site as well as a mounting frame for the installation for operation of the compounder upon a substructure at the job site, wherein the drive module is supported on at least one intermediate frame which can be secured in a position ready for operation in the supporting frame by means of detachable connections for the transport, and that there are provided underneath the at least one intermediate frame supports which extend through openings in the bottom of the supporting frame for support at the job site upon the substructure and so dimensioned in height that the intermediate frame is slightly lifted from the bottom of the supporting frame, when the supporting frame is placed upon the substructure.
The solution according to the invention is based on the principle to provide a substantially complete decoupling between drive module and the supporting frame, designed as three-dimensional framework, for the compounder, whereby the functionality of the supporting frame remains fully intact for the transport from the manufacturer""s factory to the job site. This means that the mixing unit is fixedly connected with the supporting frame during transport. The connection is implemented by detachable connections which are removed again at the job site. The essence of the invention is the securement of the drive module, which in most cases is comprised of an electric motor and a coupled gearbox, upon a common intermediate frame for both units. It is also possible, although less advantageous, to provide separate intermediate frames for both units. The intermediate frame can be effectively lifted from the supporting frame by means of supports, which can be placed at the job site upon the substructure underneath the intermediate frame through openings in the bottom of the supporting frame, or are already mounted to the intermediate frame. The intermediate frame rests thus only during transport directly on the supporting frame and is fixed thereto. At the job site, the intermediate frame is slightly lifted from the bottom of the supporting frame, after detaching the fixation, when the supporting frame is placed upon the substructure. It is hereby essential that the drive module, despite this elevation, virtually retains the ready position which has been maintained also during the transport process. Thus, all connections, which have been established during assembly at the manufacturer""s end, remain virtually unchanged during transport and after the final installation at the job site. The height of the supports is so dimensioned that lifting of the intermediate frame from the supporting frame is suitably in the range of, for example, few millimeters. It is only required to prevent a direct physical contact between the intermediate frame and the supporting frame.
Suitably, the provision of a separate machine frame for the mixing unit, which preferably is a separate twin screw extruder rotating in same direction or opposite direction, is omitted in the compounder according to the invention. This is easily possible because the processing unit of the mixing unit, i.e. the extruder barrel, can be securely connected directly with the drive module, which in turn can be fixed via the intermediate frame. The processing unit can hereby be suspended freely, when the length is short enough. In case of a long processing unit, the provision of an additional support is recommended. Such a support could be realized on the supporting frame as this would be provided anyway for the transport process. Through intervention of respective vibration dampers, the introduction of vibrations via the processing unit can be attenuated. Clearly preferred is however a solution in which at least one additional support is provided for the processing unit and extended through an opening in the bottom of the supporting frame, which rests upon the substructure, for direct support upon the substructure.
To compensate for manufacturing tolerances of the contact points of the substructure for the supports, it may be advantageous to configure the supports for carrying the intermediate frame and/or carrying the processing unit in a height-adjustable manner. Hereby, the supports may be provided with screw feet which can be secured in the final mounting position.
Suitably, the supporting frame is equipped with a compartment which is enclosed by walls and separated from the part of the supporting frame which houses the mixing unit. This enclosed compartment preferably accommodates the necessary switch cabinets for the measurement, control and regulation technologies as well as energy supply. Control may be realized by a typical PC system which can also be accommodated in this enclosed compartment and thereby remains unaffected from mechanical vibrations. This compartment may also be kept free from other interfering influences such as moisture and high temperature in a simple manner through air-conditioning.
Preferably, the supporting frame has a substantially block-shaped configuration and has outer dimensions and connection dimensions and connection devices of a standard container. This is highly advantageous with respect to handling during road transport or rail transport.
Suitably, the roof of the supporting frame is configured for foot traffic and provided with fastening devices for mounting additional devices for the compounder. Then, the attachment of, for example, a weigh feeder or a further supporting frame with the required metering devices can easily be mounted to the roof of the supporting frame. The necessary line connections for a weigh feeder are already mounted inside the supporting frame in the form of prepared interfaces. Of course, during transport, the weigh feeder is dismantled to prevent damage.